Field of the invention
[0001] The invention relates to a LED-based lighting component and to an assembly method
of such a component. It specifically relates to a reflector mounted to a printed circuit
board holding LEDs.
Description of the related art
[0002] LED lighting systems offer significant advantages over traditional incandescent,
HID and fluorescent lamps. LEDs are of smaller size, offer higher reliability, longer
operational life and lower energy consumption. However, there are specific requirements
when using LEDs. As increased operating temperature significantly reduces lifetime,
cooling is of high importance. Furthermore, most LED chips are approximately isotropic
light sources with a lambertian light distribution, which must be adapted to specific
requirements of a lighting system.
[0003] The
US patent application publication 2008/027894181 A1 discloses a printed circuit board with LEDs soldered thereon. For adapting the light
distribution, injection molded reflectors are positioned above each individual LED.
The disadvantage is that the reflectors must be manually assembled to the printed
circuit board. This is a complex and time-consuming step. Furthermore, the reflectors
are comparatively complex and expensive. Because assembly is a different manufacturing
step, the requirements of the assembly process with respect to tolerances and the
risk of mechanical damages is very high.
Summary of the invention
[0004] The problem to be solved by the invention is to provide means for cooling and adapting
the light distribution of LEDs mounted to a carrier like a printed circuit board.
Furthermore, the solution should be inexpensive and suitable for manufacturing in
large volumes.
[0005] Solutions of the problem are described in the independent claims. The dependent claims
relate to further improvements of the invention.
[0006] A preferred embodiment relates to a LED-based lighting component comprising a printed
circuit board and a plurality of LEDs mounted thereon. Preferably, a reflector is
placed on the printed circuit board. Preferably, the reflector is a surface mount
component. This means it is a component to which the surface mount technology is applicable,
which may be mounted on soldering pads at the printed circuit board or glued to the
surface of the printed circuit board. Usually surface mount components do not require
holes or are otherwise penetrating the printed circuit board. Anyway, there may be
specific embodiments of the surface mounted reflector which have posts to be held
within holes of the printed circuit board. Preferably the surface mount reflector
is of sheet metal with reflector surfaces formed thereof. It may also comprise any
ceramic or plastic materials, which withstand the soldering process. Preferably, these
materials have at least one metallized or at least light reflecting surface. The reflector
surfaces extend over the surface of the printed circuit board. They guide the light
of the LED chips, which often have an approximated lambertian light distribution.
The surface mount reflector can easily be manufactured from sheet metal by a simple
process of punching and bending the reflector surfaces of the main plane, which is
defined by the metal sheet. This allows for a precise and inexpensive manufacturing
process of high volumes of the surface mount reflector.
[0007] It is further preferred, if the surface mount reflector has at least one mounting
pad. Most preferably, the surface mount reflector has at least two, three or four
mounting pads. The surface mount reflector may be mounted to the printed circuit board
by gluing or soldering preferably of the at least one mounting pad to the printed
circuit board. Most preferably the surface mount reflector is placed to the printed
circuit board by a SMD pick and place machine. Preferably, this is done in the same
process as placing the LEDs and other electronic components to the printed circuit
board, thus reducing tolerances and assembly time.
[0008] Furthermore, the printed circuit board may be inserted into a frame. For this purpose,
the frame may have one or two braces. The frame may also serve as mechanical support,
a heat sink or as an insulator of the assembly. The frame may be a strand casted,
pultruded or extruded profile. It preferably has overhangs to hold the surface mount
reflector down to the printed circuit board and further to fix the reflector and the
printed circuit board within the frame. To improve the fixation within the frame,
the reflector may have springs. These assert a predetermined force to the reflector
and therefore to the printed circuit board. This may further press the printed circuit
board to the frame, further improving heat transfer to the frame. For easy assembly
the printed circuit board is pushed into an opening at the end of the profile. Slipping
of the printed circuit board within the profile my may be prevented by end caps or
by a lug or a screw.
[0009] According to a further preferred embodiment, a surface mount reflector comprises
at least one reflector surface. The surface mount reflector is preferably made of
metal, which may be aluminum or brass, or any other material, which has a light reflecting
surface. Most preferably the surface mount reflector is a metal sheet and the at least
one reflector surface is punched from this metal sheet. The at least one reflector
surface may be part of the surface of the metal sheet which is bent into an angle
from a main plane of the metal sheet. Preferably, the surface mount reflector has
at least one mounting pad for mounting the surface mount reflector to a printed circuit
board. It is most preferred to have at least two, three or four mounting pads to allow
stable positioning of the surface mount reflector on the printed circuit board.
[0010] In a further embodiment, the surface mount reflector has at least one blanking or
opening for the at least one LED, thus surrounding the LED on the printed circuit
board. The surface mount reflector may have further blankings leaving space for further
electronic components on the printed circuit board.
[0011] In a preferred embodiment, the printed circuit board has a first surface mount reflector
and a second surface mount reflector, being located at opposing sides of a LED. In
another embodiment, the printed circuit board has four surface mount reflectors being
located at or four sides of a rectangular LED. There may be any other number or any
other shape of the surface mount reflectors.
[0012] Although it is preferred, that the surface mount reflectors reflect light from the
LED into a different direction than it was emitted from the LED, the surface mount
reflector may also and/or alternatively shade light from the LED, thus preventing
light radiating into unwanted directions.
[0013] A further advantage is that the surface mount reflector may act as a heat sink for
dissipating heat from the LED. For this purpose it is preferred if the surface mount
reflector comprises of a heat conductive material. It is further preferred, if the
surface mount reflector is mounted close to the LED and preferably contacts at least
the same metallized layer as the thermal interface of the LED to improve heat transfer.
[0014] In a further embodiment, the surface mount reflector may be mounted at the opposite
side of the LEDs of the printed circuit board. In this case, the printed circuit board
may have at least one opening or slot, through which the individual surface mount
reflector surfaces can penetrate the printed circuit board.
[0015] In a further embodiment, a frame may be provided. The frame may act as at least one
of a mechanical support, a heat sink, an insulator. The frame may interact with springs
on the surface mount reflectors for pressing the printed circuit board to the frame
and therefore improving heat transfer. Preferably, the frame is a profile, which may
be manufactured by strand casting or pultrusion or extrusion. The frame is preferably
made of metal or ceramics, most preferably of aluminum.
[0016] Mounting the printed circuit board within the frame is a very simple procedure. The
first step the surface mount reflector is positioned on or preferably fixed to the
printed circuit board. In the next step, the printed circuit board is inserted into
the frame by pushing them into a slot opening at one end of the frame. The frame may
further support alignment of the surface mount reflector and the printed circuit board.
[0017] By means of a flat spring of the at least one surface mount reflector, the printed
circuit board is held in a predetermined position relative to the frame.
[0018] This embodiment results in a defined pressure of the printed circuit board (PCB)
to the frame without any additional elements (e.g. screws, glue,..). Due to the permanent
elastic deformation of the flat spring, the thermal resistance between the PCB and
the frame will not change over lifetime.
[0019] A method according to the invention comprises at least the steps of placing at least
one LED on a printed circuit board and placing at least a surface mount reflector
to the same printed circuit board in the proximity of the at least one LED. The sequence
of these steps can be reversed. Both steps are preferably done within the same manufacturing
process. It is preferred, if both steps are done by pick and place machines. Therefore,
no manual handling of the components is necessary. Consequently, a very high precision
of placement and very low mechanical tolerances specifically of the relative positions
of the at least one LED and the at least one surface mount reflector can be achieved.
This results in low tolerances of the optical system and a very precise radiation
pattern. Furthermore automatic handling prevents damaging or at least maladjustment
of the at least one surface mount reflector. Most preferably, precision can be further
increased by doing both steps with the same pick and place machine. After placing
the at least one LED and the at least one surface mount reflector to the printed circuit
board, it may be heated by a reflow oven and/or a solder wave to solder the at least
one LED and the at least one surface mount reflector to the printed circuit board.
Description of Drawings
[0020] In the following, the invention will be described by way of example, without limitation
of the general inventive concept, on examples of embodiment with reference to the
drawings.
Figure 1 shows a preferred embodiment of the invention.
Figure 2 shows the preferred embodiment in a side view.
Figure 3 shows the preferred embodiment in a sectional view.
Figure 4 shows the preferred embodiment assembled into a frame.
Figure 5 shows a second embodiment of the invention.
Figure 6 shows the second embodiment in a side view.
Figure 7 shows another embodiment, with four reflector surfaces.
Figure 8 shows a basic arrangement of a surface mounted reflector.
Figure 9 shows a circular surface mount reflector. A
Figures 10 to 14 show different embodiments of surface mounted reflectors.
[0021] In figure 1, a preferred embodiment according to the invention is shown. A LED 20
is mounted to a printed circuit board 10. Furthermore, two surface mount reflectors
80, 90 are located on the printed circuit board. These surface mount reflectors each
have at least one reflecting surface 81, 91. Preferably, the surface mount reflectors
80, 90 have at least one, preferably three or four mounting pads 82, 83, 84, 92, 93,
94 for mounting and fixing the surface mount reflectors to the surface of the printed
circuit board. These mounting pads may be glued and/or soldered to the printed circuit
board. The surface mount reflectors may be placed at the printed circuit board by
a pick and place machine. Furthermore there may be flat springs 85, 86, 95, 96. In
general, there may be any number of LEDs and of surface mount reflectors on the printed
circuit board.
[0022] Figure 2 shows the preferred embodiment in a side view. Here the surface mount reflectors
80, 90 are shown from their sides standing with the mounting pads 82, 84, 92, 94 on
the printed circuit board 10.
[0023] In figure 3, a sectional view is shown. It specifically shows the flat Springs 85
and 86 extending from mounting pads 82 and 83.
[0024] In figure 4, an embodiment with assembled printed circuit board and frame is shown.
The printed circuit board 10 is assembled with a frame 100. The frame has at least
one overhang 101, 102, preferably two overhangs, to hold the printed circuit board
10 together with surface mount reflector 80 within the frame. The at least one overhang
100 preferably interacts with the at least one flat spring 85, 86 to assert a predetermined
force to the surface mount reflector. Frame 100 may be designed to act as a mechanical
support structure and/or a heat sink and/or electrical insulator for the assembly.
[0025] In figure 5, a further embodiment according to the invention is shown. At least one
LED 20 is mounted to a printed circuit board 10. Furthermore, a surface mount reflector
30 is located on the printed circuit board. This surface mount reflector has at least
one blanking or opening 36 for a LED. It further has at least one reflector surface
32. Preferably, there is at least a second reflector surface 33, preferably at the
opposite side of the LED in relation to the first reflector 32 surface. Preferably,
the reflector surfaces 32, 33 are punched out and bent upwards from the surface mount
reflector. This may result in at least one additional blanking 37. There may be further
electronic components like LED drivers placed on the printed circuit board within
the at least one additional blanking 37.
[0026] Figure 6 shows this embodiment in a side view. Here the surface mount reflector 30
is shown from its side with the reflector surfaces 32, 33 bent upwards in an angle
from the reflector base 31, which is located on the printed circuit board 10.
[0027] Figure 7 shows another embodiment, where four reflector surfaces are provided. A
first reflector surface 32, second reflector surface 33, third reflector surface 34
and fourth reflector surface 35 enclose the LED, which is placed on a printed circuit
board within blanking 36 at four sides.
[0028] Figure 8 shows a basic arrangement of a surface mounted reflector 40 in relationship
to a LED 20. The surface mount reflector 40 is a component, which is mounted in close
proximity to the LED 20 with its reflecting surface 41 directed towards the LED. There
may be further surface mount reflectors 40a with reflecting surfaces 41a arranged
in close proximity to the LED 20.
[0029] Figure 9 shows a circular surface mount reflector 40 having a reflecting surface
41 around LED 20.
[0030] Figures 10 to 14 show different embodiments of surface mounted reflectors 40, 50,
60, 70 with their reflecting surfaces 41, 51, 61, 71 directed towards LED 20 mounted
on the printed circuit board 10.
[0031] List of reference numerals
- 10
- printed circuit board
- 20
- LED
- 30
- surface mount reflector
- 31
- reflector base
- 32, 33, 34, 35
- reflector surfaces
- 36
- blanking for LED
- 37
- blanking
- 40, 50, 60, 70
- surface mount reflectors
- 41, 51, 61, 71
- reflector surfaces
- 80
- surface mount reflector
- 81
- reflector surface
- 82, 83, 84
- mounting pads
- 85,86
- flat springs
- 90
- surface mount reflector
- 91
- reflector surface
- 92, 93, 94
- mounting pads
- 95, 96
- flat springs
- 100
- frame
- 101, 102
- overhang
1. LED-based lighting component comprising at least:
- at least one LED (20) mounted to a printed circuit board (10)
- at least one surface mount reflector (80) located on the printed circuit board,
the surface mount reflector having at least one reflector surface (81) oriented towards
the at least one LED.
2. LED-based lighting component according to claim 1,
characterized in, that
the at least one surface mount reflector comprises of a metal sheet.
3. LED-based lighting component according to any one of the preceding claims,
characterized in, that
the at least one surface mount reflector comprises any ceramic or plastic material,
which withstand the soldering process.
4. LED-based lighting component according to any one of the preceding claims,
characterized in, that
the at least one surface mount reflector comprises at least one heat conductive material.
5. LED-based lighting component according to any one of the preceding claims,
characterized in, that
the at least one surface mount reflector is thermally connected to the at least one
LED to act as a heat sink.
6. LED-based lighting component according to any one of the preceding claims,
characterized in, that
a first surface mount reflector (80) and the second surface mount reflector (90) are
located at opposing sides of the at least one LED (20).
7. LED-based lighting component according to any one of the preceding claims,
characterized in, that
the component comprises a frame (100) for holding the printed circuit board (10).
8. LED-based lighting component according to claim 8,
characterized in, that
the surface mount reflector (80) has at least one spring (85, 86) to interact with
the frame (100) to hold the surface mount reflector (80) down to the printed circuit
board (10).
9. Method for manufacturing a LED-based lighting component according to any one of the
preceding claims, comprising the steps of:
a) positioning and fixing at least one LED (20) on a printed circuit board (10), and
b) positioning and fixing a surface mount reflector (80) on a printed circuit board
(10).
10. Method for manufacturing a LED-based lighting component according to claim 9,
characterized in, that
both steps are done with the same pick and place machine.